Decolorizing titanium tetrachloride



Patented Nov. 7, 1939 I nEooLoRi'zmo. 1 I oHLoaInn j Frederick-Gage, Akron, 0hio,= assignor to'Pittsv burgh Plate Glass Company, Allegheny County, a

" Pa, a corporati'on of Pennsylv nia l No Drawing. Applicati lil ebr ll a 't i3, I938,

'13 Claims. teller-ti),

This invention relates to'the decolorizing oftitanium tetrachloride; 'W'hile'pure titanium tetrachloride is a water White liquid, the product which is obtainedbychlorination of titanium compounds and the commercial products generally available on the market have a distinct"'yellowish cast. Prior to this'invention, decolorizing this liquidhas been attempted by treatment with certain metals, suchas reduced'iron or sodium amalgam. Some decolorizing may be secured in this manner, but in general, it is found that the treated liquid does not remain colorless permanently and that it is contaminated with metallic impurities. This is highly, undesirable" when titanium tetrachloride is being decomposed into ti- ,tanium dioxide pigment, since the metallic impurities tend'to' reduce the whiteness of the pigment produced.

'l'naccordance with my invention, I have found that titanium tetrachloride may be decoloriz ed to form a water white liquid by treatment with lower valent titanium compounds. I have found that especially effective results may be obtained by treatment with chlorides of titanium, such as titanium trichloride, or titanium dichloride. other titanium compounds which may be found suitable are titanium tribromide, titanium triiodide, titanous sulfate, etc. However, it is preferred to use the lower valent chlorides of titanium in order to avoid contamination of the material.

The treatment may be secured by any convenient method which will insure the required contact. I have found that very satisfactory results may be obtained by vigorously agitating a mixture of titanium tetrachloride and titanium trichloride while heating under a reflux condenser and subsequently distilling and condensing the titanium tetrachloride.

Since the tetrachloride is readily hydrolyzed in a moist atmosphere, it is preferred to carry this process out in the presence of a dry inert gas. Dry carbon dioxide or nitrogen are suitable for this purpose although other gases may be resorted to. I

The concentration of the lower valent titanium salt required depends to a great extent upon the color of the'product being treated. In general, it is preferred to maintain an excess of this salt, and it has been determined that concentrations in excess of about 2.0% titanium trichloride yield satisfactory products in most cases.

The time for which the mixture is refluxed likewise dependsupon the degree of coloration of the product being treated. In general, refluxing QchIOride'and WQ 'h r "tilled rapidly an atmosphere of dry C02. The

were vigorouslyag'itated and heatedl under a"rej'iicr p mow-15 1.0. then distill ed i apidlyln' 'pensed with. The, residue remaining after dis- 5 tillation will;in -general,contain'more or. less .titanous salts and may Ice-reused in aysubseduent treatment offurtheramounts of titanium tetrachloride. p Y N v 1 Thefollowing examples-are illustrat ,ive: 10 'Ea. ampZ'-I- 1 OO-parts of yellow'titanium'tetraq a parts of titanium trichloridewere vigorously agitatedand heated undera reflux condenser ,at a temperature of 135 C. for a period of The treated mixture was then dis-. 15

product produced was water-white.

"Example "IL parts of yellow titanium tetrachloride and 3; parts of titanium trichloride ondenser at a t mperature "of l35f C fora 0 The treated-mixture was an atrr'iosphere'of dryCOa The product produced was Water white.

Example lIL-lOO parts of yellow titanium 25 tetrachloride and 5 parts of titanium dichloride were vigorously agitated and heated under a re flux condenser at a temperature of C. for a period of two hours. The treated mixture was then distilled rapidly in an atmosphere of dry 30 nitrogen. The product produced was water white.

Thetitanium compound may be introduced into the tetrachloride in any convenient manner. By one very efiective method, I may reduce a 35 portion of the tetrachloride by suitable means, for example, by introduction of hydrogen, thereby generating the lower valent chloride in situ. However, the compound may be added in the form of a solid or as a solution as desired. Aqueous solutions of the compound preferably should be avoided due to the rapidity with which the tetrachloride hydrolyzes.

Although the invention has been described in connection with the specific details of certain embodiments thereof, it is not intended that such details shall be regarded as limitations uponthe scope of the invention except insofan as in-- cluded in the accompanying claims.

I claim:

1. A method of decolorizing colored titanium tetrachloride which comprises contacting the same with a lower valent titanium compound in an amount sufficient and for the time required 65 same with a lower valent titanium-chloride in an amount sufiicient and for the time required to remove at least a substantial portion of the color from the tetrachloride.v Y H 4. A method of decolorizing colored titanium tetrachloride which comprises contacting the Same with titanium trichloride in an amount sufficient and for the time required to remove at least a substantial portion of the color from" the tetrachloride.

5. .A method of decoloriz ing colored titanium tetrachloride which comprises contacting the same with titanium dichloride in an amount sufficient and for the time required to remove at least a substantial portion of the color from the tetrachloride.

.6. A method of decoloriz'ing colored titanium tetrachloride which comprises heating the same in the presence oi a lower valent titanium compound'iri an amount sufiicient to remove atleast asiibstantial portion of the color from the tetrachloride arid subseqiiently distilling the heated titanium tetraehloride 7. A method of decolorizing colored t tan um tetrachloride which comprises heating the same ifi'thepfes'ence Ora lower valent titanium halide in an amount sufiicient to remove at least a substa'ntial portion of the color from the tetrachloride and subsequently distilling the heated titanium tetrachloride.

8. A method of decoloriiingcolored titanium tetrachl(' rid 'e which comprises heating the same in the presence of a lower valent titanium chlo ride in an amount suflicient to remove at least a substantial portion of the color from the tetrachloride and subsequently distilling the heated titanium tetrachloride.

9. A method of decolorizing colored titanium tetrachloride which comprises heating the same in the presence of titanium trichloride in an *amount sufllcient to remove at least a substantial portion of the color from the tetrachloride and subsequently distilling the heated titanium tetrachloride.

10. A method of decolorizing colored titanium tetrachloride which comprises heating the same in the presence of titanium dichloride in an amount sufficient to remove at least a substantial' portion of the color from the tetrachloride and subsequently distilling the heated titanium tetrachloride.

11. A method of decolorizing colored titanium tetrachloride which comprises heating the same in the presence of titanium dichloride in an amount sufficient to remove at least a substantial portion of the color from the tetrachloride and subsequently distilling the heated titanium tetrachloride and decolorizing further quantities of titanium tetrachloride by treating said quantities f with the residue from said distillation.

12. A method of de'colorizing colored titanium tetrachloride which comprises heating the same with a lower valent titanium compound in an amount sufficient and for thetime required to remove at least a substantial portion of the color from the tetrachloride.

v13. A method of decolorizin'g colored titamum tetrachloride which comprises heating the same with titanium trichloride in an amount sufficient and for the time required to remove at least a substantial portion of the color from the tetrachloride.

FREDERICK GAGE. 

